The present invention relates to apparatuses and methods for the fabrication of semiconductor devices. More particularly, the present invention relates to a target that deposits a material layer on a semiconductor device.
Sputtering is a method of depositing a material layer on a semiconductor substrate. A typical sputtering apparatus includes a target and a substrate support pedestal enclosed in a sputtering chamber. The target contains a material that is deposited on a substrate. The target is typically affixed to the top of the sputtering chamber, but is electrically isolated from the sputtering chamber walls. A voltage source maintains the target at a negative voltage with respect to the sputtering chamber walls, creating a voltage differential which excites a gas contained within the sputtering chamber into a plasma. Plasma ions are generated and directed to the target where plasma ion momentum transfers to target atoms, causing the target atoms to be ejected (i.e., to sputter) from the target. The sputtered target atoms deposit on the substrate, thereby forming a thin film.
However, a portion of the sputtered target atoms become scattered in the plasma and eventually accumulate on other surfaces within the sputtering chamber, including the sidesurfaces of the target. The sputtered target atoms, which do not directly deposit on the substrate, are referred to as sputtered particles. A portion of the sputtered particles may tend to flake or crumble off the sidesurfaces of the target as the sputtering chamber thermally cycles, particularly when a significant amount of sputtered particles has accumulated thereon. Such flaking or crumbling sputtered particles may settle on, and thereby contaminate the substrate. Accordingly, in order to reduce this type of contamination, a need exists in the semiconductor fabrication field for an apparatus and method that reduces substrate contamination that occurs due to flaking or crumbling of sputtered particles which accumulate on the sidesurfaces of the target.
The present invention provides an inventive target having a front surface and one or more sidesurfaces. A coating layer is applied to the inventive sputtering target""s sidesurface. Characteristics of the coating layer promote adhesion between the sputtering target""s sidesurfaces and sputtered particles which may accumulate thereon, thus preventing the accumulated sputtered particles from flaking off or crumbling off the sidesurfaces of the inventive sputtering target and settling onto a substrate positioned therebelow. Accordingly, the present invention may reduce substrate contamination, thereby increasing sputtering chamber yield and reducing substrate costs. In a further aspect, the coating may also be applied to a portion of the target""s backing plate.
Other, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings.